I like the channel for a similar reason I enjoy skillshots more than targeted abilities: the timing, prediction, and suspense of whether or not it will hit make it feel more satisfying. Personally, I think its perfect right now.
Its not hard to shove the lane as Xerath: melee minions won't be lost to your minions after an Arcanopulse, and ranged minions are likely to not be taking hits and be open for a second Arcanopuse.
Xerath scales strongly into the late game, and his Q gets on a fairly low CD to pick off melee minions.
When I play Xerath, I use his ult's low cool-down to harass with it: Xerath does not excell at catching and bursting champions down in lane without a gank, but as a difficult to avoid, artillery ranged harass his ultimate can go a long way to shoving enemies out of lane.
I just want it a little shorter so his combo feels better when used.
Remember I wanted something to help his early farming a bit, before a Deathcap.
Whenever I hit six I try to get a kill as much as possible, E, easy stun proc with one R, Q, R, R, and try to Q again if they survived. If they survive, then next time I would poke them down before killing.